Can you use corn starch to thicken a soup?

Corn starch can be used as a thickener for your soups. The proportion of corn starch to liquid is one part corn starch to two parts liquid. This slurry is added to your soup slowly and stirred in to thicken the broth. With corn starch as a thickener, you must be sure to never boil your soup because the corn starch will break down.